I am relatively new to OpenWrt/Linux and had a question about modifying the packet content in a probe request sent from a sta client.  I have a hard time figuring out where such modifications should be made and how to figure out where such modification should be made.  For instance, is it required to modify source code in firmware for wilink wifi module, source in kernel, or could changes to this packet be simply done by modifying a configure file to a utility?  Specifically, I need to enable WPS support in the probe request that is sent to the AP. 
Any help/pointers would be greatly appreciated.  Thanks!